This circuit is very useful in our life, it’s used in most devices like thermostat of cars and computers…

The main criteria is protecting the electrical appliance from overheating so that it can work safely for longer period of time.1- ARDUINO Uno 2- Temperature sensor (LM 35)3- Transistor4- Light Emitting Diode

5- Diode (Flyback/protection diode)

6- Fan-Consists of both a physical programmable circuit board and a piece of software-With some simple code, the ARDUINO can control the circuitARDUINO Uno

-Used to measure the change in temperature by a material called silicon that its capability of electricity change according to the change in temperature

contains 3 legs:-Right one for connecting to the ground.-Left one for connecting to Vcc.-The middle one for sensing the temperature

Temperature sensor (LM 35)

- It’s used as a switch in our circuit.

- transistor contains: (Emitter-Collector-Base)

- Type: NPN

Transistor (switch)

The circuit Indicator lamps

It allows an electric current to pass in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction).

• The main idea of our circuit is to control temperature which is measured by ‘LM35DZ’ using ARDUINOTemp > 40Temp < 2020 < Temp < 40the red led will emit and the Fan will start working to reduce amount of heat to work safelyTemp < 20the green led will emit to indicate that everything is okay and the device connected to the fan working safely.20 < Temp < 40The yellow led to indicate that temperature is medium, less than 40 and more than 20Temp > 40StepsWriting program CodeWriting program CodeCode SampleRunning circuit simulation on Proteus Testing the circuit on a test boardTesting the circuit on a test boardCreating PCB(Printed Circuit Board) This included the following stepsDesigning the circuit on EAGLE .Printing the design on the copper board.Soaking the board in HNO3 ACID.Drilling .Soldering.